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Wet Chemical Etching of AlN Single Crystals
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- Journal:
- Materials Research Society Internet Journal of Nitride Semiconductor Research / Volume 7 / 2002
- Published online by Cambridge University Press:
- 13 June 2014, e4
- Print publication:
- 2002
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Anisotropic chemical etching is an important means for characterizing the polarity and defect density of single crystals. In this letter, we present the results of our studies on the etching of bulk AlN crystals in aqueous potassium hydroxide solution. The nitrogen polarity (0001) basal plane initially etched rapidly, while the aluminum polarity basal plane, and prismatic (1
00) planes were not etched. The etch rate of the nitrogen polarity basal plane eventually decreased to zero, as the surface became completely covered with hexagonal hillocks which were bounded by {101} planes. The hillock density for the self-seeded AlN crystals studied was typically in the range of 5×107cm −2 to 109cm −2. From our analysis of etched AlN crystals, we infer that freely nucleated crystals predominately have the nitrogen to aluminum direction pointing out from the nucleation surface, that is the ends of the AlN crystals facing the source are aluminum polarity.
00) planes were not etched. The etch rate of the nitrogen polarity basal plane eventually decreased to zero, as the surface became completely covered with hexagonal hillocks which were bounded by {1